The first electronic amplification of sound was done with Vacuum Tubes. We have pre-amp, power and rectifier vacuum tubes among other types in New Old Stock from the golden era of American & European manufacturing as well as current production tubes from today.
Vacuum Tube - 417A, Western Electric, Triode
9-pin miniature triode with an indirectly heated cathode. It is intended primarily for grounded-grid operation in the input stage of broad band amplifiers.
Vacuum Tube - 420-A / 5755, Western Electric, Dual Triode
Triode, Double, Western Electric brand